Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press  

The authors have previously developed a compact, light-weight air flow control valve, which realizes continuous flow control. The vibration produced by a piezoelectric device (PZT) was used to excite particles confined in a flow channel to control the valve opening for the developed control valve. Therefore, the voltage applied to the PZT can be changed to continuously control the flow rate. A new working principle was developed for the control valve to stabilize flow rate characteristics. Different types of particles were used to change the valve opening condition. A prototype was manufactured to demonstrate the effectiveness of the control valve.

DOI： 10.20965/ijat.2016.p0540

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Authorship：Lead author  

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Authorship：Lead author   Language：Japanese   Publisher：The Japan Fluid Power System Society  

The purpose of this study is the development of a valve that can precisely control pneumatic cylinders. The valve is lightweight and has simple structure. The valve uses a piezoelectric oscillator which is driven in the resonance mode, and it can control flow rate by controlling the amplitude of the particle excitation. In this report, we have designed a new prototype for the purpose of high controllability. We have applied a non-linear control algorithm to control Q-V nonlinearlity of this valve. We found that this control works well to realize linear Q-V characteristics.

DOI： 10.5739/jfps.43.117

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/10009556897?from=CiNii

Authorship：Lead author   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：American Society for Precision Engineering, ASPE  

Recently sapphire is widely used for LED substrate. In the planarization process of sapphire, lapping is used before polishing. However, machining time of lapping takes more than 30 minutes because sapphire is hard material. Superfinishing process can be substitute for the lapping. Superfinishing uses fixed abrasive stones, and it is possible to process sapphire in shorter time. Surface roughness of the lapping process is 2nmRa. Therefore, superabrasive stones are suitable for superfinishing. Then, vitrified-bonded diamond superabrasive stones with different grain diameter were developed. Superfinishing performances of those stones were compared. Subsequently multistage superfinishing was examined by combining diamond stones in descending order of grain diameter. The target roughness 2nmRa was achieved in 8 minutes of 4-stage superfinishing. In this study, we have examined three different combinations to improve multistage superfinishing of sapphire.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>Diamond cutting tools shows severe wear in turning of steels. In previous paper, it was shown that carbides on ferrite phase, which were precipitated by carburization, suppressed the diamond tool wear. In this paper, detailed distribution of constituents of the carbides was analyzed by EDS (energy-dispersive X-ray spectroscopy). In addition, characteristics of each carbide such as occupancy, diameter, and degree of circularity were measured. Results indicate that those characteristics of the carbides influence suppression of the tool wear.</p>

DOI： 10.1299/transjsme.17-00161

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Japan Society of Mechanical Engineers  

In ultra-precision cutting of polycrystalline material with single crystal diamond tool, grain boundary steps become obvious on the machined surface due to crystal anisotropy between adjacent grains. Therefore, to establish ultra-precision cutting technology, it is necessary to clarify the micro cutting mechanism of singlecrystal material. In our past work, we have focused on elastic recovery of single crystal copper in micro groove cutting. However, affected layer were formed at the stage of planar cutting, which was a prior process of groove cutting. It was difficult to observe the influence of crystal anisotropy once the affected layer was formed. Thus, appropriate cutting conditions of prior process are necessary to minimize the affected layer. In this study, single crystal copper (111) plane, one of slip planes, was used as a cutting surface.We defined [112] direction as 0° and conducted prior cutting process at 13 directions ranging from -60° ([211]) to 60° ([121]). Cutting forces were measured and hardness of the finished surfaces were examined. Chips, tools and cutting surface were observed with an electron microscope. The Schmidt factor of each slip system was calculated from the measured three-component forces. Then, we investigated the influence of crystal orientation on cutting mechanism and machined surface in prior cutting. As a result, cutting parallel to [121] direction (60°) generated the best cutting surface. In contrast, cutting parallel to [112] direction (0°) generated the most defective cutting surface. In addition, the finished surface had periodicity of 120° with good surface and defective surface, respectively. Results suggest that the slip systems and its Schmidt factors may explain the periodicity.

DOI： 10.1299/jsmelem.2017.9.091

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Japan Society of Mechanical Engineers  

Diamond tools wear extremely in single point turning of steels. It is thought that carbon atoms in diamond diffuse into iron. Characteristics of steels can be widely changed by heat treatment and surface modification. In our past work, we have focused on heat treatment and have changed the microstructure to suppress the tool wear. We have found carbides precipitated in α-phase suppress the tool wear. Then, we have studied on carburized steels. Tool wear was examined in comparison with element concentration, hardness, and carbide area ratio of carburized steels. Accordingly, large-size and high-circularity carbides precipitated on grain boundaries were related to increase the tool wear. However, it was not clear which factors may suppress the tool wear. In this study, past experimental data was used to examine relation between tool wear and microstructure of carburized steels. We used 21 sets of data, which contains element concentration, hardness, and carbide area ratio of carburized JIS SKD61 steels. Based on it, a decision tree which explains tool wear was made by using C4.5 classification algorithm. The decision tree revealed carburized steels without carbides whose area is ranging from 1 to 3 μm2 and whose circularity is less than 0.5 tend to increase the tool wear. On the other hand, carburized steels with above-mentioned carbides, and with carbides whose area is ranging from 0.07 to 1 μm2 and whose circularity is less than 0.5 suppress tool wear the best. Those results suggest that the decision tree can be used to predict microstructure which may suppress tool wear effectively.

DOI： 10.1299/jsmelem.2017.9.092

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1186/s40648-017-0093-3

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Other Link： http://link.springer.com/article/10.1186/s40648-017-0093-3/fulltext.html

Language：Japanese   Publisher：The Japan Society for Precision Engineering  

Recently, demands have increased on fabricating complex and accurate structures by ultra-precision cutting. However, the machinability is influenced by crystallographic orientations in micron/submicron cutting. In our past work, it was clear that the crystal anisotropy affected the elastic recovery in submicron groove cutting of single crystal copper. Before the experiments, three-step cutting, i.e., rough cutting, intermediate cutting, and finish cutting, have been employed to flattening single crystal copper surface. The depth of affected layer was thinned by increasing the number of intermediate and finish cutting. Nevertheless, few microns of affected layer remained on finished surface. The rough cutting step is considered to cause the remaining affected layer. In this paper, we have investigated the effect of cutting conditions of the rough cutting step to reduce the depth of affected layer. The Schmidt factor of each slip system was calculated from measured cutting forces. Results suggest that the slip system and its Schmidt factor may explain the machinability, and results indicate that the thickness of affected layer decrease with an increase in cutting speed.

DOI： 10.2493/jjspe.83.967

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press  

In planarization processes of sapphire, lapping process takes a long time because sapphire is a hard material. In contrast, superfinishing, which involves fixed abrasive machining, can substitute for lapping, and it would be possible to shorten the amount of processing time. In this work, vitrified-bonded diamond superabrasive stones with different grain diameters are developed. Then, multistage superfinishing is investigated by combining these stones. Results indicate that the multistage process is capable of producing a 2 nmRa surface, equivalent of a lapped surface in less than 10 min. To improve the process of multistage superfinishing, a removal amount estimation method is developed based on the real contact pressure calculation. The working area ratio of the stone was calculated by considering elastic deformation during superfinishing. The contact ratio of sapphire is calculated considering the roughness of the pre-finished surface and grain depth of cut. Accordingly, the real contact pressure is calculated to estimate the removal amount during superfinishing and finished surface roughness was expected.

DOI： 10.20965/ijat.2017.p0742

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：20th International Symposium on Advances in Abrasive Technology, ISAAT 2017  

In this study, high accuracy and high efficiency processing of sapphire was investigated. In order to attain the target surface roughness 2 nmRa equivalent to lapping process, multistage superfinishing with plural diamond superabrasive stones was carried out. In our past work, superfinishing with four different grain size stones was examined. The multistage process was capable of producing surface roughness of 2 nmRa in 8 min. To improve multistage superfinishing, removal amount estimation method considering elastic deformation during superfinishing was developed. However, measured removal amount in long time superfinishing was smaller than that of estimated amount. It was considered that superfinishing efficiency decreased after pre-finished surface roughness was removed. Therefore, removal amount estimation method was improved by changing removal amount estimation formula after removing total height of roughness profile Rt of pre-finished surface. Results indicated that estimated removal amount approximated to the measured amount in long time superfinishing with SD20000 stone.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：euspen  

Severe tool wear occurs when commercial steels are single-point diamond turned. Thermochemical reactions such as carbon dissociation and diffusion cause the severe wear. Nitrided steels are known to diminish the wear. In this paper, different kinds of steels were nitrided to examine the diminishing effect of tool wear. Nitrided layers are formed when nitriding of steels. The top of the layer is hard but fragile, thus the wear experiments were implemented after removing those top layers. The depth and the hardness of the nitrided layers vary due to the compositions of steels. Steels that contain large amount of chromium form thin and hardened layers. Then chromium nitrides and iron nitrides are generated inside the layers. In contrast, steels that contain low amount of chromium form thick but less hardened layers that consist only of iron nitrides. Results indicate that the more the amount of chromium in steels, the more diminishing of diamond tool wear. In addition, the less the wear, the more accurate the copying of tools' outline. Results also suggest that chromium nitrides aggregated in grain boundaries effectively diminished the wear. Those nitrides are considered to prevent carbon atoms of diamond from fast diffusion into grain boundaries.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：American Society for Precision Engineering, ASPE  

Sapphire is widely used for the LED substrate. In the planarization process of sapphire, lapping is used as the former process of polishing. However, the machining time of lapping takes about 30 minutes because sapphire is hard material. The superfinishing process can be substitute for the lapping. Superfinishing is a fixed abrasive machining, and it is possible to process sapphire by short time. The target surface roughness of the lapping process is 2nmRa. Therefore, superabrasive stones are used for the superfinishing. Then, vitrified-bonded diamond superabrasive stones with different grain diameter and different grade were developed, and superfinishing performances of those stones were compared. As a result, the diamond superabrasive stones with lower grades are more suitable stones as the former process of the polishing. However, those stones reached the stone life when the superfinishing with were done from the ground surface that was the former process of the lapping, and surface roughness were not able to be achieved. And some deep scratches of the former process remained when the amount of superfinishing process was not enough. At that point, multistage superfinishing was examined by combining some diamond superabrasive stones with different grain diameter. Finally, the removal amount estimation method was developed based on the real contact pressure presumption under the multistage process aiming at the achievement of the target roughness by short time.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：American Society for Precision Engineering, ASPE  

In this study, we investigated tool wear suppression effect of nitrides in diamond turning of nitrided steels. We used three types of steels: stainless steel
hot work tool steel
and nitride steel. After quenched and tempered, those steels were nitrided by gas nitriding. Composition of surfaces were identified by X-ray diffraction method before and after nitriding. Precipitated nitrides in nitrided steels depended on composition of steels. After pre-finishing, we investigated machinability test of nitrided steels. Maximum wear was observed at the tool nose. The amounts of wear in diamond turning of nitrided steels were much smaller than those of quenched and tempered steels. Add to this, nitrided steels precipitating particular nitrides suppressed wear of diamond tool than other nitrided steels. Surface integrity was also improved as the wear was suppressed.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：euspen  

In this study, superfinishing characteristics of single crystal silicon using vitrified bonded superabrasive stones containing soft barium sulphate (BaSO4) abrasives were investigated. BaSO4 can act as an oxidizing agent in superfinishing. A thermodynamic analysis suggests that BaSO4 reacts with silicon forming oxides. Characteristic X-ray patterns revealed that layers that covered silicon heated with BaSO4 abrasives consisted of silicon and oxide. On the basis of these results, vitrified diamond stones containing BaSO4 abrasives were evaluated through superfinishing of single crystal silicon. It was found that the addition of BaSO4 abrasives improved the dressing intervals of diamond stones. After finishing with diamond stones containing BaSO4 abrasives, superfinishing characteristics of single crystal silicon with soft BaSO4 stones were investigated. Results indicate that BaSO4 stones can finish single crystal silicon to 1.5 nm Ra in 2 minutes under the condition that can promote chemical reactions.

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Language：Japanese   Publisher：The Japan Society for Abrasive Technology  

Our goal is the development of a design system for mechanochemical superabrasive stones containing both cBN and CeO₂ abrasives. As the first step, we have already developed a morphological structure model for the stone using fractal modeling techniques. As the second step, this paper describes the surface topography model for the stone. We have already proposed a surface topography model for the stone containing only cBN grains. This model can describe the surface topography with the same fractal dimension of grain distribution as the morphological structure model. Therefore, we have improved the model by preparation of the describing parameters for each grain and the changes in these parameters through the describing algorithm. As a result, the model bears resemblance to the real stone in topography and fractal dimension in each grain of the topography model is approximately equal to the morphological structure model.

DOI： 10.11420/jsat.57.453

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Other Link： https://jlc.jst.go.jp/DN/JALC/10021320100?from=CiNii

Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：Japanese  

DOI： 10.5739/jfps.43.117

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Venue：Las Vegas, Nevada, USA  

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Venue：京都教育文化センター  

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Venue：兵庫県立大学  

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Venue：Kobe, Japan  

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Venue：Kobe,Japan  

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Venue：関西大学  

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Venue：関西大学  

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Venue：金沢大学  

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Venue：金沢大学  

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Venue：中央大学  

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Venue：中央大学  

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Venue：中央大学  

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Venue：Okinawa, Japan  

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Venue：Hiroshima, Japan  

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Venue：Hiroshima, Japan  

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Venue：大阪大学  

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Venue：大阪大学  

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Venue：大阪大学  

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Venue：大阪大学  

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Venue：大阪大学  

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Venue：福岡工業大学  

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Venue：福岡工業大学  

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Venue：Tours, France  

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Venue：Bremen, Garmany  

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Venue：TAIPEI, TAIWAN  

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Venue：Okinawa, Japan  

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Venue：Dubrovnik, Croatia  

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Venue：東京大学  

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Venue：大阪工業大学  

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Venue：Budapest, Hungary  

Finalist in the Best Student Paper Award

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Venue：東北大学  

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Venue：The Westin Boston Waterfront, Boston, MA, USA  

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Venue：東北大学  

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Venue：東北大学  

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Venue：東北大学  

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Venue：Crowne Plaza St. Paul – Riverfront, St. Paul, MN, USA  

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